Matt Lutz, a former forecaster for the Sawtooth National Forest Avalanche Center, stands next to the crown of a large avalanche in an east-facing bowl on Durrance Peak north of Ketchum in late December 2006. Photo courtesy Sawtooth National Forest Avalanche Center.

The Sawtooth National Forest Avalanche Center is urging people to be extra cautious in the backcountry this weekend as avalanche danger continues to rise.

The National Weather Service issued a heavy snow warning for the Sawtooth Mountains and Wood River region through Friday afternoon with over a foot of snow expected in the upper elevations. More storms are expected over the weekend into next week.

The dry, cool weather that persisted through January created a sugary snowpack throughout much of the area that will struggle to support the added weight of new snow—a bricks-on-potato-chips type scenario.

"As the snow accumulates, so will the likelihood of unstable avalanche conditions similar to those that killed six backcountry enthusiasts last weekend," said Janet Kellam, director of the Avalanche Center.

Heavy snow that fell in Utah, eastern Idaho and Montana in mid-February created highly unstable conditions that killed five snowmobilers and a skier in five separate incidents last weekend.

Saturday, Feb. 17, was the deadliest day: Two snowmobilers were killed in an avalanche in Montana's Big Belt Mountains; one snowmobiler died in an avalanche in the Palisades Peak area in eastern Idaho; and two snowmobilers were killed in separate incidents in northern and southwest Utah.

The following day, a 17-year-old boy was killed while skiing with his father and brother in the backcountry adjacent to Snowbasin resort in Utah. The victim was not wearing a beacon.

Kellam foresees a similarly dangerous scenario developing in the local mountains over the next couple days.

"Significant snowfall, wind and warming temperatures will all increase the avalanche danger in some areas," Kellam said. "Tracks on a slope do not indicate it is safe if weak, loose snow lies beneath the surface slab.

"Don't head out without avalanche rescue gear—an avalanche beacon, shovel and probe—and the knowledge to use them."

The avalanche danger was considerable in the north valley, Sawtooths and western Smokies on Thursday, and Kellam said that danger will also emerge in the central and south valley as new snow accumulate

"A deep slab avalanche danger has been creeping up on us due to accumulated February snow on a weak, January snowpack," Kellam wrote in Thursday's advisory, which can be viewed daily at sawtoothavalanche.com, or heard via a voice recording at 622-8027.

The
Idaho Mountain Express is distributed free to residents and guests
throughout the Sun Valley, Idaho resort area community. Subscribers to the
Idaho Mountain Express will read these stories and others in this week's
issue.